Method of improving the frictional properties of functional fluids

ABSTRACT

A method of improving the brake and clutch capacity of a functional fluid comprising adding a friction-modifying amount of a polyalkenyl sulfonate to the functional fluid, wherein the polyalkenyl sulfonate is an alkali metal or alkaline earth metal salt of a polyalkylene sulfonic acid derived from a mixture of polyalkylenes comprising greater than about 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers.

[0001] The present invention relates to functional fluids useful insystems requiring coupling, hydraulic fluids and/or lubrication ofrelatively moving parts. In particular, the present invention relates toa method of improving the brake and clutch capacity of functional fluidsuseful in wet clutch and/or wet brake systems, such as in automatictransmissions and tractors.

BACKGROUND OF THE INVENTION

[0002] Modern lubricating oil formulations are formulated to exactingspecifications often set by original equipment manufacturers. To meetsuch specifications, various additives are used, together with base oilof lubricating viscosity. Depending on the application, a typicallubricating oil composition may contain dispersants, detergents,anti-oxidants, wear inhibitors, rust inhibitors, corrosion inhibitors,foam inhibitors just to name a few. Different applications will governthe type of additives that will go into a lubricating oil composition.

[0003] A functional fluid is a term which encompasses a variety offluids including but not limited to tractor hydraulic fluids, automatictransmission fluids including continuously variable transmission fluids,manual transmission fluids, hydraulic fluids, power steering fluids,fluids related to power train components and fluids which have theability to act in various different capacities. It should be noted thatwithin each of these fluids such as, for example, automatic transmissionfluids, there are a variety of different types of fluids due to thevarious transmissions having different designs which have led to theneed for fluids of markedly different functional characteristics.

[0004] Tractor hydraulic fluids and automatic transmission fluids areexamples of functional fluids having very specific frictionrequirements. Because such fluids work in wet brake and/or wet clutchsystems, the fluid must assist in smooth engagement of these brakes andclutches while maintaining desirably high frictional properties foreffective brakes and clutches. These fluids require high frictioncoefficients. For example, tractor hydraulic fluids that involve wetbrake systems must have a high friction coefficient to be effective.Further, automatic transmission fluids must have enough friction for theclutch plates to transfer power. However, the friction coefficient offluids has a tendency to decline due to the temperature effects as thefluid heats up during operation. It is important that the tractorhydraulic fluid or automatic transmission fluid maintain its highfriction coefficient at elevated temperatures, otherwise brake systemsor automatic transmissions may fail.

SUMMARY OF THE INVENTION

[0005] The present invention provides a method of improving the brakeand clutch capacity of a functional fluid, especially tractor hydraulicfluids, automatic transmission fluids including continuously variabletransmission fluids, comprising adding to the functional fluid afriction-modifying amount of a polyalkenyl sulfonate having a Total BaseNumber (TBN) of about 0 to about 60 and is an alkali metal or alkalineearth metal salt of a polyalkylene sulfonic acid derived from a mixtureof polyalkylenes comprising greater than 20 mole percent alkylvinylidene and 1,1-dialkyl isomers.

[0006] The present invention further provides a method of improving thebrake and clutch capacity of a functional fluid, especially tractorhydraulic fluids, automatic transmission fluids including continuouslyvariable transmission fluids, comprising adding to the functional fluida friction-modifying amount of a polyalkenyl sulfonate having a TBN ofgreater than about 60 to about 400 and is an alkali metal or alkalineearth metal salt of a polyalkylene sulfonic acid derived from a mixtureof polyalkylenes comprising greater than about 20 mole percent alkylvinylidene and 1,1-dialkyl isomers.

[0007] Preferably, the alkyl vinylidene isomer is a methyl vinylideneisomer and the 1,1-dialkyl isomer is a 1,1-dimethyl isomer.

[0008] The polyalkylene employed has a number average molecular weightof about 168 to about 5,000. Preferably, the polyalkene ispolyisobutene. More preferably, the polyalkene is polyisobutene and themolecular weight distribution of the polyisobutenyl sulfonic acids hasat least about 80% of the polyisobutenyl sulfonic acids molecularweights separated by even multiples of about 56 daltons. Mostpreferably, the polyalkene is polyisobutene and less than about 20% ofthe polyisobutenyl sulfonic acids in the molecular weight distributionof the polyisobutenyl sulfonic acids contain a total number of carbonatoms that is not evenly divisible by about four.

[0009] A further embodiment of the present invention provides a methodwherein the functional fluid is a tractor hydraulic fluid or anautomatic transmission fluid.

[0010] Among other factors, the present invention is based on thesurprising discovery that a friction-modifying amount of the polyalkenylsulfonates of the present invention provides improved brake and clutchcapacity when used in a functional fluid. The benefits of the presentinvention are apparent in functional fluids useful in systems requiringcoupling and lubricating of relatively moving parts, such as wet clutchand/or brake systems, as in automatic transmissions and tractors. Otheradvantageous properties provided by the present invention are goodstability, water dispersing properties, less foaming tendencies, andrust protection.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Prior to discussing the present invention in detail, thefollowing terms will have the following meanings unless expressly statedto the contrary.

Definitions

[0012] The term “alkaline earth metal” refers to calcium, barium,magnesium, strontium, or mixtures thereof.

[0013] The term “alkyl” refers to both straight- and branched-chainalkyl groups.

[0014] The term “alkylene” refers to straight- and branched-chainalkylene groups having at least 2 carbon atoms. Typical alkylene groupsinclude, for example, ethylene (—CH₂CH₂—), propylene (—CH₂CH₂CH₂—),isopropylene (—CH(—CH₃)CH₂—), n-butylene (—CH₂CH₂CH₂CH₂—), sec-butylene(—CH(CH₂CH₃)CH₂—), n-pentylene (—CH₂CH₂CH₂CH₂CH₂—), and the like.

[0015] The term “metal” refers to alkali metals, alkali earth metals, ormixtures thereof.

[0016] The term “polyalkyl” or “polyalkenyl” refers to an alkyl oralkenyl group which is generally derived from polyolefins which arepolymers or copolymers of mono-olefins, particularly 1-mono-olefins,such as ethylene, propylene, butylene, and the like. Preferably, themono-olefin employed will have about 2 to about 24 carbon atoms, andmore preferably, about 3 to about 12 carbon atoms. More preferredmono-olefins include propylene, butylene, particularly isobutylene,1-octene and 1-decene. Polyolefins prepared from such mono-olefinsinclude polypropylene, polybutene, especially polyisobutene, and thepolyalphaolefins produced from 1-octene and -decene.

[0017] The term “Total Base Number” or “TBN” refers to the amount ofbase equivalent to the milligrams of KOH in 1 gram of sample. Thus,higher TBN numbers reflect more alkaline products and therefore agreater alkalinity reserve. The TBN of a sample can be determined byASTM Test No. D2896 or any other equivalent procedure. In general terms,TBN is the neutralization capacity of one gram of the lubricatingcomposition expressed as a number equal to the mg of potassium hydroxideproviding the equivalent neutralization. Thus, a TBN of 10 means thatone gram of the composition has a neutralization capacity equal to 10 mgof potassium hydroxide.

[0018] As stated above, the present invention provides a method ofimproving the brake and clutch capacity of a functional fluid by addinga friction-modifying amount of a polyalkenyl sulfonate to the functionalfluid. The polyalkenyl sulfonate is an alkali metal or alkaline earthmetal salt of a polyalkylene sulfonic acid derived from a mixture ofpolyalkylenes comprising greater than about 20 mole percent alkylvinylidene and 1,1-dialkyl isomers.

The Polyalkenyl Sulfonate

[0019] The polyalkenyl sulfonates of the present invention are preparedby reacting a polyalkenyl sulfonic acid (prepared as described below)with a source of an alkali metal or alkaline earth metal. The alkalimetal or alkaline earth metal can be introduced into the sulfonate byany suitable means. One method comprises combining a basically reactingcompound of the metal, such as the hydroxide, with the polyalkenylsulfonic acid. This is generally carried out in the presence of ahydroxylic promoter such as water, alcohols such as 2-ethyl hexanol,methanol or ethylene glycol, and an inert solvent for the sulfonate,typically with heating. Under these conditions, the basically reactingcompound will yield the metal sulfonate. The hydroxylic promoter andsolvent can then be removed to yield the metal sulfonate.

[0020] Under certain circumstances, it may be more convenient to preparean alkali metal polyalkenyl sulfonate and convert this material bymetathesis into an alkaline earth metal sulfonate. Using this method,the sulfonic acid is combined with a basic alkali metal compound such assodium or potassium hydroxide. The sodium or potassium sulfonateobtained can be purified by aqueous extraction. Then, the sodium orpotassium sulfonate is combined with an alkaline earth metal salt toform the alkaline earth metal sulfonate. The most commonly used alkalineearth metal compound is a halide, particularly a chloride. Typically,the sodium or potassium sulfonate is combined with an aqueous chloridesolution of the alkaline earth metal and stirred for a time sufficientfor metathesis to occur. Thereafter, the water phase is removed and thesolvent may be evaporated, if desired.

[0021] The preferred sulfonates are alkaline earth metal sulfonates,especially those of calcium, barium and magnesium. Most preferred arethe calcium and magnesium sulfonates.

[0022] The polyalkenyl sulfonates of the present invention are eitherneutral or overbased sulfonates. Overbased materials are characterizedby a metal content in excess of that which would be present according tothe stoichiometry of the metal cation in the sulfonate said to beoverbased. Thus, a monosulfonic acid when neutralized with an alkalineearth metal compound, such as a calcium compound, will produce a normalsulfonate containing one equivalent of calcium for each equivalent ofacid. In other words, the normal metal sulfonate will contain one moleof calcium for each two moles of the monosulfonic acid.

[0023] By using well known procedures, overbased or basic complexes ofthe sulfonic acid can be obtained. These overbased materials containamounts of metal in excess of that required to neutralize the sulfonicacid. Highly overbased sulfonates can be prepared by the reaction ofoverbased sulfonates with carbon dioxide under reaction conditions. Adiscussion of the general methods for preparing overbased sulfonates andother overbased products is disclosed in U.S. Pat. No. 3,496,105, issuedFeb. 17, 1970 to LeSuer, which in incorporated by reference in itsentirety.

[0024] The amount of overbasing can be expressed as a Total Base Number(“TBN”), which refers to the amount of base equivalent to the milligramsof KOH in one gram of sulfonate. Thus, higher TBN numbers reflect morealkaline products and therefore a greater alkalinity reserve. The TBNfor a composition is readily determined by ASTM test method D664 orother equivalent methods. The overbased polyalkenyl sulfonates of thisinvention can have relatively low TBN, i.e., about 0 to about 60, morepreferably, about 0 to about 30; or relatively high TBN, i.e., greaterthan about 60 to about 400, more preferably about 250 to about 350.

[0025] The polyalkenyl sulfonates of the present invention are useful asadditives in functional fluids in amounts sufficient to provide improvedbrake and clutch capacity. They have good water dispersion properties, alight color and provide good performance characteristics.

Polyalkenyl Sulfonic Acid

[0026] The polyalkenyl sulfonic acids of the present invention areprepared by reacting a mixture of polyalkenes comprising greater thanabout 20 mole percent alkyl vinylidene and 1,1-dialkyl isomers with asource of sulfur trioxide —SO₃—. The source of —SO₃— can be a mixture ofsulfur trioxide and air, sulfur trioxide hydrates, sulfur trioxide aminecomplexes, sulfur trioxide ether complexes, sulfur trioxide phosphatecomplexes, acetyl sulfate, a mixture of sulfur trioxide and acetic acid,sulfamic acid, alkyl sulfates or chlorosulfonic acid. The reaction maybe conducted neat or in any inert anhydrous solvent. The conditions forsulfonation are not critical. Reaction temperatures can range from about−30° C. to about 200° C. and depends on the particular sulfonating agentemployed. For example, acetyl sulfate requires low temperatures forreaction and elevated temperatures should be avoided to preventdecomposition of the product. Reaction time can vary from a few minutesto several hours depending on other conditions, such as reactiontemperature. The extent of the reaction can be determined by titrationof sulfonated polyalkene after any free sulfuric acid has been washedout.

[0027] Typical mole ratios of sulfonating agent to polyalkene can beabout 1:1 to about 2:1.

[0028] The preferred sulfonating agent is acetyl sulfate (or a mixtureof sulfuric acid and acetic anhydride which forms acetyl sulfate insitu) which produces the polyalkenyl sulfonic acid directly. Othersulfonating agents, such as a mixture of sulfur trioxide and air, mayproduce a sultone intermediate that needs to be hydrolyzed to thesulfonic acid. This hydrolysis step can be very slow.

[0029] The polyalkenes used to prepare the polyalkenyl sulfonic acid area mixture of polyalkenes having about 12 to about 350 carbon atoms. Themixture comprises greater than about 20 mole percent, preferably greaterthan about 50 mole percent, and more preferably greater than about 70mole percent alkylvinylidene and 1,1-dialkyl isomers. The preferredalkylvinylidene isomer is a methyl vinylidene isomer, and the preferred1,1-dialkyl isomer is a 1,1-dimethyl isomer.

[0030] The polyalkenes have a number average molecular weight in therange of about 168 to about 5,000. Preferably, the polyalkenes havenumber average molecular weights of about 350 to about 2,300; morepreferably, about 350 to about 1,000; and most preferably, about 350 toabout 750.

[0031] The preferred polyalkene is polyisobutene. Especially preferredare polyisobutenes made using BF₃ as catalyst.

[0032] U.S. Pat. No. 5,408,018, which issued on Apr. 18,1995 to Rath andwhich is incorporated by reference in its entirety, and the referencescited therein describe a suitable process for the production ofpolyisobutenes that contain greater than about 20 mole percentalkylvinylidene and 1,1-dialkyl isomers.

[0033] Typically, when polyisobutenyl sulfonic acids or sulfonates areprepared from polyisobutene having a mole percent of alkylvinylidene and1,1-dialkyl isomers greater than about 20% is used to preparepolyisobutenyl sulfonic acids or sulfonates, the molecular weightdistribution of the resulting product has at least about 80% of thepolyisobutenyl sulfonic acids or sulfonates whose molecular weights areseparated by even multiples of about 56 daltons. In other words, lessthan about 20% of the polyisobutenyl sulfonic acids or sulfonates in themolecular weight distribution of the sulfonic acids or sulfonatescontain a total number of carbon atoms that is not evenly divisible byabout four.

Functional Fluids

[0034] The functional fluids of the present invention use base oilsderived from mineral oils, synthetic oils or vegetable oils. A base oilhaving a viscosity of at least about 2.5 cSt at about 40° C. and a pourpoint below about 20° C., preferably at or below 0° C., is desirable.The base oils may be derived from synthetic or natural sources. Baseoils may be derived from any of one or combination of Group I throughGroup V base stocks as defined in American Petroleum InstitutePublication 1509, which is herein incorporated for all purposes.

[0035] Mineral oils for use as the base oil in this invention include,for example, paraffinic, naphthenic and other oils that are ordinarilyused in lubricating oil compositions.

[0036] Vegetable oils may include, for example, canola oil or soybeanoil.

[0037] Synthetic oils include, for example, both hydrocarbon syntheticoils and synthetic esters and mixtures thereof having the desiredviscosity. Hydrocarbon synthetic oils may include, for example, oilsprepared from the polymerization of ethylene, i.e., polyalphaolefin orPAO, or from hydrocarbon synthesis procedures using carbon monoxide andhydrogen gases such as in a Fisher-Tropsch process. Useful synthetichydrocarbon oils include liquid polymers of alpha olefins having theproper viscosity. Especially useful are the hydrogenated liquidoligomers of C₆ to C₁₂ alpha olefins such as 1-decene trimer. Likewise,alkyl benzenes of proper viscosity, such as didodecyl benzene, can beused. Useful synthetic esters include the esters of monocarboxylic acidsand polycarboxylic acids, as well as mono-hydroxy alkanols and polyols.Typical examples are didodecyl adipate, pentaerythritol tetracaproate,di-2-ethylhexyl adipate, dilaurylsebacate, and the like. Complex estersprepared from mixtures of mono and dicarboxylic acids and mono anddihydroxy alkanols can also be used. Blends of mineral oils withsynthetic oils are also useful.

Other Additive Components

[0038] The following additive components are examples of some of thecomponents that can be favorably employed in the present invention.These examples of additives are provided to illustrate the presentinvention, but they are not intended to limit it:

[0039] A. Metal Detergents

[0040] Sulfurized or unsulfurized alkyl or alkenyl phenates, sulfonatesderived from synthetic or natural feedstocks, carboxylates, salicylates,phenalates, sulfurized or unsulfurized metal salts of multi-hydroxyalkyl or alkenyl aromatic compounds, alkyl or alkenyl hydroxy aromaticsulfonates, sulfurized or unsulfurized alkyl or alkenyl naphthenates,metal salts of alkanoic, acids, metal salts of an alkyl or alkenylmultiacid, and chemical and physical mixtures thereof.

[0041] B. Anti-Oxidants

[0042] Anti-oxidants reduce the tendency of mineral oils to deterioratein service which deterioration is evidenced by the products of oxidationsuch as sludge and varnish-like deposits on the metal surfaces and by anincrease in viscosity. Antioxidants may include, but are not limited to,such anti-oxidants as phenol type (phenolic) oxidation inhibitors, suchas

[0043] 4,4′-methylene-bis(2,6-di-tert-butylphenol),

[0044] 4,4′-bis(2,6-di-tert-butylphenol),4,4′-bis(2-methyl-6-tert-butylphenol),

[0045] 2,2′-methylene-bis(4-methyl-6-tert-butylphenol),4,4′-butyldene-bis(3-methyl-6-tert-butylphenol),

[0046] 4,4′-isopropylidene-bis(2,6-di-tert-bulylphenol),2,2′-methylene-bis(4-methyl-6-nonylphenol),

[0047] 2,2′-isobutylidene-bis(4,6-dimethylphenol),

[0048] 2,2′-methylene-bis(4-methyl-6-cyclohexylphenol),2,6-di-tert-butyl-1-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,

[0049] 2,4-dimethyl-6-tert-butyl-phenol,2,6-di-tert-dimethylamino-p-cresol,

[0050] 2,6-di-tert-4-(N,N′-dimethylaminomethylphenol),4,4′-thiobis(2-methyl-6-tert-butylphenol),2,2′-thiobis(4-methyl-6-tert-butylphenol),

[0051] bis(3-methyl-4-hydroxy-5-tert-butylbenzyl)-sulfide, and

[0052] bis(3,5-di-tert-butyl-4-hydroxybenzyl). Diphenylamine-typeoxidation inhibitors include, but are not limited to, alkylateddiphenylamine, phenyl-α-naphthylamine, and alkylated-α-naphthylamine.Other types of oxidation inhibitors include metal dithiocarbamate (e.g.,zinc dithiocarbamate), and methylenebis (dibutyldithiocarbamate). Theanti-oxidant is generally incorporated into an oil in an amount of about0 to about 10 wt %, preferably 0.05 to about 3.0 wt %, per total amountof the engine oil.

[0053] C. Anti-Wear/Extreme Pressure Agents

[0054] As their name implies, these agents reduce wear of movingmetallic parts. Examples of such agents include, but are not limited to,phosphates, phosphites, carbamates, esters, sulfur containing compounds,molybdenum complexes, zinc dialkyldithiophosphate (primary alkyl,secondary alkyl, and aryl type), sulfurized oils, sulfurizedisobutylene, sulfurized polybutene, diphenyl sulfide, methyltrichlorostearate, chlorinated naphthalene, fluoroalkylpolysiloxane, andlead naphthenate.

[0055] D. Rust Inhibitors (Anti-Rust Agents)

[0056] 1) Nonionic polyoxyethylene surface active agents:polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether,polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether,polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether,polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitolmonooleate, and polyethylene glycol monooleate.

[0057] 2) Other compounds: stearic acid and other fatty acids,dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts ofheavy sulfonic acid, partial carboxylic acid ester of polyhydricalcohol, and phosphoric ester.

[0058] E. Demulsifiers

[0059] Addition product of alkylphenol and ethylene oxide,polyoxyethylene alkyl ether, and polyoxyethylene sorbitan ester.

[0060] F. Friction Modifiers

[0061] Fatty alcohols, 1,2-diols, borated 1,2-diols, fatty acids,amines, fatty acid amides, borated esters, and other esters.

[0062] G. Multifunctional Additives

[0063] Sulfurized oxymolybdenum dithiocarbamate, sulfurizedoxymolybdenum organo phosphorodithioate, oxymolybdenum monoglyceride,oxymolybdenum diethylate amide, amine-molybdenum complex compound, andsulfur-containing molybdenum complex compound.

[0064] H. Viscosity Index Improvers

[0065] Polymethacrylate type polymers, ethylene-propylene copolymers,styrene-isoprene copolymers, hydrogenated styrene-isoprene copolymers,polyisobutylene, and dispersant type viscosity index improvers.

[0066] I. Pour Point Depressants

[0067] Polymethyl methacrylate.

[0068] J. Foam Inhibitors

[0069] Alkyl methacrylate polymers and dimethyl silicone polymers.

EXAMPLES

[0070] The invention will be further illustrated by the followingexamples, which set forth particularly advantageous method embodiments.While the Examples are provided to illustrate the present invention,they are not intended to limit it. This application is intended to coverthose various changes and substitutions that may be made by thoseskilled in the art without departing from the spirit and scope of theappended claims.

Example 1 Preparation of Test Oils

[0071] The test fluids were prepared by dissolving 4.0 wt % sulfonatesdescribed in Table 1 in SAE 30 weight mineral base oil. The compositionof the test fluids are shown in Table 2. TABLE 1 Sulfonate DescriptionType Feed Stock % Ca TBN LOB sulfonate I LOB sulfonate Polyisobuteneaverage 2.55 14 of Invention mw 550 Comparative LOB sulfonate Natural2.33 19 Example A Comparative LOB sulfonate Mixed (natural and 2.34 14Example B synthetic) HOB Sulfonate of HOB sulfonate Polyisobuteneaverage 12.3 296 Invention) mw = 550 Comparative HOB sulfonate Synthetic12.7 320 Example C Comparative HOB sulfonate Natural 12.5 320 Example D

[0072] TABLE 2 Test Fluid Compositions Test Oil % Component in mixtureComponent 1 2 3 4 5 6 7 LOB sulfonate I of 4.0 Invention ComparativeExample 4.0 A Comparative Example 4.0 B HOB Sulfonate II of 4.0Invention Comparative Example 4.0 C Comparative Example 4.0 D Base Oil96.0 96.0 96.0 96.0 96.0 96.0 100.0

Example 2 Measurement of Friction Coefficients

[0073] Friction coefficients of the test fluids prepared in Example 1were measured using a micro-clutch apparatus made by Komatsu Engineeringand following the Komatsu KES 07.802 procedure. That is, the disc andthe plates as specified in the procedure were contacted with thepressure of 4 kgf/cm² against the disc rotating at 20 rpm in presence ofadditive component dissolved in mineral oil. The friction coefficientwas measured at room temperature (25° C.), 60° C., 80° C., 100° C., 120°C., and 140° C. The results are shown in Table 3. TABLE 3 KomatsuMicro-clutch Friction Test Results Friction Coefficients at IndicatedTest Temperatures Test Fluid 25° C. 40° C. 60° C. 80° C. 100° C. 120° C.140° C. 1 (Invention) 0.162 0.168 0.173 0.182 0.184 0.185 0.181 2 0.1510.152 0.156 0.157 0.152 0.146 0.138 3 0.147 0.151 0.153 0.147 0.1410.133 0.126 4 (Invention) 0.163 0.164 0.171 0.176 0.180 0.187 0.190 50.150 0.148 0.126 0.113 0.109 0.111 0.117 6 0.157 0.159 0.156 0.1510.150 0.152 0.158 7 (Base Oil) 0.162 0.164 0.163 0.158 0.153 0.149 0.149

[0074] From these results, it can been seen that the PIB sulfonates ofthe present invention in Test Fluids 1 and 4 provided high frictionalproperties compared to the commercial comparative LOB or HOB sulfonates(Test Fluids 2, 3, 5, and 6) and the base oil (no sulfonate)(Test Fluid7).

What is claimed is:
 1. A method of improving the braking and clutchcapacity of a functional fluid, said method comprising adding afriction-modifying amount of a polyalkenyl sulfonate to said functionalfluid, said polyalkenyl sulfonate having a TBN of about 0 to about 60wherein said polyalkenyl sulfonate is an alkali metal or alkaline earthmetal salt of a polyalkylene sulfonic acid derived from a mixture ofpolyalkylenes comprising greater than about 20 mole percent alkylvinylidene and 1,1-dialkyl isomers.
 2. The method according to claim 1,wherein the polyalkenyl sulfonate has a TBN of about 0 to about
 30. 3.The method according to claim 1, wherein the mixture of polyalkenescomprises greater than about 50 mole percent alkyl vinylidene and1,1-dialkyl isomers.
 4. The method according to claim 1, wherein themixture of polyalkenes comprises greater than about 70 mole percentalkyl vinylidene and 1,1-dialkyl isomers.
 5. The method according toclaim 1, 2, 3, or 4 wherein the alkyl vinylidene isomer is a methylvinylidene isomer, and the 1,1-dialkyl isomer is a 1,1-dimethyl isomer.6. The method according to claim 1, wherein the number average molecularweight of the polyalkene is about 168 to about 5,000.
 7. The methodaccording to claim 1, wherein the number average molecular weight of thepolyalkene is about 350 to about 2,300.
 8. The method according to claim1, wherein the number average molecular weight of the polyalkene isabout 350 to about 1,000.
 9. The method according to claim 1, whereinthe number average molecular weight of the polyalkene is about 350 toabout
 750. 10. The method according to claim 1, wherein the polyalkeneis polyisobutene.
 11. The method according to claim 10, wherein thepolyisobutene is made using a BF₃ catalyst.
 12. The method according toclaim 1, wherein the polyalkene is polyisobutene and the molecularweight distribution of the polyisobutenyl sulfonic acids has at leastabout 80% of the polyisobutenyl sulfonic acids molecular weightsseparated by even multiples of about 56 daltons.
 13. The methodaccording to claim 1, wherein the polyalkene is polyisobutene and lessthan about 20% of the polyisobutenyl sulfonic acids in the molecularweight distribution of the polyisobutenyl sulfonic acids contain a totalnumber of carbon atoms that is not evenly divisible by about four. 14.The method according to claim 1, wherein the functional fluid is anautomatic transmission fluid or hydraulic fluid.
 15. The methodaccording to claim 14, wherein the functional fluid is a hydraulicfluid.
 16. The method according to claim 15, wherein the hydraulic fluidis a tractor hydraulic fluid.
 17. A method of improving the braking andclutch capacity of a functional fluid, said method comprising adding afriction-modifying amount of a polyalkenyl sulfonate to said functionalfluid, said polyalkenyl sulfonate having a TBN of greater than about 60to about 400 wherein said polyalkenyl sulfonate is an alkali metal oralkaline earth metal salt of a polyalkylene sulfonic acid derived from amixture of polyalkylenes comprising greater than about 20 mole percentalkyl vinylidene and 1,1-dialkyl isomers.
 18. The method according toclaim 1, wherein the polyalkenyl sulfonate has a TBN of about 250 toabout
 350. 19. The method according to claim 18, wherein the mixture ofpolyalkenes comprises greater than about 50 mole percent alkylvinylidene and 1,1-dialkyl isomers.
 20. The method according to claim16, wherein the mixture of polyalkenes comprises greater than about 70mole percent alkyl vinylidene and 1,1-dialkyl isomers.
 21. The methodaccording to claim 16, 17, 18, or 19 wherein the alkyl vinylidene isomeris a methyl vinylidene isomer, and the 1,1-dialkyl isomer is a1,1-dimethyl isomer.
 22. The method according to claim 16, wherein thenumber average molecular weight of the polyalkene is about 168 to about5,000.
 23. The method according to claim 16, wherein the number averagemolecular weight of the polyalkene is about 350 to about 2,300.
 24. Themethod according to claim 16, wherein the number average molecularweight of the polyalkene is about 350 to about 1,000.
 25. The methodaccording to claim 16, wherein the number average molecular weight ofthe polyalkene is about 350 to about
 750. 26. The method according toclaim 16, wherein the polyalkene is polyisobutene.
 27. The methodaccording to claim 26, wherein the polyisobutene is made using a BF₃catalyst.
 28. The method according to claim 16, wherein the polyalkeneis polyisobutene and the molecular weight distribution of thepolyisobutenyl sulfonic acids has at least about 80% of thepolyisobutenyl sulfonic acids molecular weights separated by evenmultiples of about 56 daltons.
 29. The method according to claim 16,wherein the polyalkene is polyisobutene and less than about 20% of thepolyisobutenyl sulfonic acids in the molecular weight distribution ofthe polyisobutenyl sulfonic acids contain a total number of carbon atomsthat is not evenly divisible by about four.
 30. The method according toclaim 16, wherein the functional fluid is a tractor hydraulic fluid oran automatic transmission fluid.
 31. The method according to claim 30,wherein the functional fluid is a tractor hydraulic fluid.